Maintaining a decades-old operating system presents a variety of development problems far outside the mainstream, with solutions for those problems requiring a great deal of creativity to not break compatibility with existing drivers or programs. One of the most pressing issues facing OS/2 is the impending removal of the legacy BIOS Compatibility Support Module (CSM) starting in January 2020.

Compared to DOS, which extensively utilizes BIOS functionality, OS/2 has hard dependencies on only a subset of BIOS features, according to Arca Noae developer Alex Taylor, in a presentation at Warpstock Europe, posted to YouTube this week. The BIOS-supplied INT10 and INT13—VGA hardware and disk I/O via BIOS, respectively—are needed to boot ArcaOS